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Need tech help please !?!

2K views 6 replies 4 participants last post by  GhostRider 
#1 ·
Here is the deal.........I am getting a very bad misfire on my car...but only when it has warmed up.......if I let it cool off, it won't do it. But it just goes and comes............any body experienced this, or dealt with this..?? Thanx.......
 
#2 ·
MATT !!!!! What's up ? I would bet it's your emissions doing this. The reason I say this ? Is because if it was backfiring on a regular basis I'd say it was a vacum leak, cracked spark plug wire, or your timing was off. Are you getting a check engine light code ?
 
#3 ·
What's new stacy?? Yeah i usually pull (3) codes every time it does it............Number 6, Number 1, and Multiple Cyl. Misfire. Let's say i was driving to work one morning, i will get there fine, 15 mins later i hop in and drive it's fine, then i stop and 15 mins after that, it is missing like hell, but if i just keep on driving it, while it is missing, it will fix it self...........sometimes it misses so bad that i can't even move...it just stalls!! I have tried every gas combination possible, replaced the cap and rotor, wires and plugs thinking it may be a heat-plastic combination, but nothing seems to work....i just don't understand why it only does it when the car is hot......... :angry:
 
#4 ·
I don't understand it either, have you tried asking the question on PT ?
 
#5 ·
Don't rule out a bad plug in a set of new plugs. Also wires can have the same issue. What brand were both? Vitek Wires are notorious for this. And if you are running Bosch platinum +4's, then remove them in favor of a nice set of NGK's imediately.

As for other aspects, how old is your fuel filter? Is your fuel pressure regulator solenoid still functioning? If in question, bypass it by hooking the vacum line from the FPR directly into the tap on the manifold.

Now, NE2 Crankshaft Position Sensor Failure could also be the cause, because this sensor sends un-conditioned Hall-effect signals to the PCME that the PCME uses to determine crankshaft angular velocity (RPM). It is typically termed "NE2" or "CKP2". This sensor is located low on the engine, on the accessory-side near the crankshaft pulley. It is nestled in behind the dipstick tube. Sometimes, if the car has had teh waterpump/timing belt off, then the mechanic may not reroute the wire behind the idler pulley assembly. This in turn will allow it to rest against the belt, which in turn will wear through it, and then you loose the signal going bac to the PCME. When you pull this code, it indicates that the crankshaft position sensor is not sending crankshaft velocity information to the PCME or the PCME is unable to make use of the signal it is sending. In 1993 and 1994 Probe V-6s when Code 2 is present, the PCM ignores it and instead relies on NE1 for crankshaft speed data. This sensor is located in the distributor. Unfortunately 1995+ GTs do not have an NE1 sensor and will not run when Code 2 is present. And as I can see in your sig, yours is a 97 :( OBD II :(

This code is memorized in the PCME non-volatile memory. Some things To Check When Diagnosing:
  • Make sure the NE2 connector and PCM connectors are clean and tight. Re-seat if necessary. On some cars that I have worked on, removing the little orange insulator in the plug resulted in a clean connection, thus eliminating the problem.
  • Check the resistance of the NE2 sensor. Unplug it and use an ohmmeter to measure the resistance across the two sensor pins which are the DB and DG wires. It should measure between 520 and 580 ohms.
  • Check for a short between the DB and DG wires and the BK/R wire (ground). If there is a short, the harness has a short.

HTH
 
#6 ·
Come to think of it, G Crankshaft Position Sensor Failure could also be the cause. That sensor sends conditioned Hall-effect signals to the PCME from within the distributor that the PCME uses to determine when #1 cylinder comes up on top-dead center (TDC). This sensor information is used to phase the sequential firing of the fuel injectors during normal SFI operation. This sensor is also known as a camshaft position sensor or CID sensor. It is a Hall-effect sensor located on the igniter in the distributor and it "fired" by a single-vane "wheel" that turns as the exhaust camshaft on the left (radiator)-side bank rotates. This code indicates that the G crankshaft (or camshaft) position sensor is not sending camshaft positional information to the PCME or the PCME is unable to make use of the signal it is sending.

When Code 3 is present, the PCME stops firing the fuel injectors in sequential mode and instead fires them in a "batch" mode since the PCME does not have any way to know where TDC on #1 is. This results in a slight loss of power and a lowering of the engine's fuel economy. but it could also be overworking the injectors, or doing something else stupid, you never know, and resulting in your cars issues. This code is memorized in the PCME non-volatile memory. So once you fix it, you'll have to clear the PCME to get the car to run normally again.

Check the condition of the 5-pin connector at the distributor. Check for +12V present at the R/BK wire to ground.
Check the seating of the 5-pin connector. Make sure it is clean and fully seated.
The igniter in the distributor is probably the most likely cause of this code although a bad PCME is not impossible.

HTH.
 
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